Kiteman I think you have made a good choice, Beretta's are very good guns and a standard 682 sporting will fit most men quite well.
Craig a lighter(e.g. a 24" sbs) gun fireing the same weight of shot will kick alot more than a heavy gun(such as a 32" O/U).
Range will be much the same on a 24" and a 32" using nitro carts, black powered used to require longer barrels due to the rate the power burns at.
The reason a sawn off will spread more is partly because you have sawn off and choke that would have been at the end of the barrels.
I'd agree with going for a 12 for both of you due to being able to get more for the same budget in a 12 than a 20, tho i would disagree that you need a minimum of 40 grams to shoot fox, i think the shot size makes more of a diffrence than the grams in the load.
Some nice looking guns for the money on http://www.ukgunroom.com/
I got one off there and was well happy with it, if it's far away can always be send to a local rfd.